Uhf transmission line switch



1952 R. SPOGEN, JR., ETAL 3,064,211

UHF TRANSMISSION LINE SWITCH Filed July 24, 1959 INVENTORS LEO R .SPaazlv JR.

ARLON J, Swevv A TTOIE'NE Y rates Unite This invention relates generally to transmission line switches and more particularly to an ultra-high frequency transmission line switch.

I In the operation of duplex radar systems, it is necessary to switch from a first antenna to a second antenna. To switch a sizeable amount of power from one antenna to the other, however, has proved to be a difficult and complex problem. Most switches that have been designed to solve this problem are either unwieldly or ineffective. They may also introduce discontinuities which may cause flash-over.

Prior switching devices that employ waveguides as the transmission medium utilize several switching methods. One method utilizes a shutter or chopper which passes completely through an opening in the waveguide. Since this switching method requires an openingin the waveguide, a measurable quantity of transmitter energy will necessarily escape from the opening. Another switching method utilizes resonant chambers which are detuned by rods, or resonant iris switches wherein the resonant irises are covered by a shutter type switch. This switching mechanism is unduly complicated to build and operate. a A

It is an object of this invention to provide a transmission line switch which is simple in construction yet elfective in its isolation.

It is still another object of this invention to provide a transmission line switch which does not have the leakage problem inherent in most transmission line switches.

This invention features a transmission line switch which is constructed of a discrete length of waveguide which is shorted at either end. An input coaxial probe is provided at the center of the waveguide section, and first and second output coaxial probes are provided on the opposite surface of the waveguide and located a discrete distance from the ends of the waveguide.

A first hinged gate is interposed between the first output and the input. A second hinged gate is interposed between the second output and the input.

An operation mechanism is connected between the hinged gates such that when the mechanism is operated in one direction, the first hinged gate will be raised to a position where it will completely block the waveguide between the input and the first output. Simultaneous with the foregoing operation, the second hinged gate will be lowered into a recess within the waveguide thereby removing the obstruction between the input and the second output. The gates are made of a conductive material and have their conductive surface interposed a predetermined distance from the input probe to create a properly spaced power transfer block as required for the coaxto-waveguide transition.

Operation of the connecting mechanism in the opposite direction will cause the first hinged gate to swing down and rest within the waveguide and simultaneously will cause the second gate to swing up and block the transmission between the input and the second output.

Further objects, features, and advantages of the invention will become apparent from the following deyarscnpuon and claim when read in view of the accompany ing drawings, in which:

FIGURE 1 is a perspective view of one embodiment of this invention; and

atent 3 @5421 l Patented Nov. 13, 1952 an external cable such as coaxial cable 25 which is securely attached to an input probe through a standard coaxial coupling to a base such as 26. Base 26 may be secured to cavity 10 by means such as welding or by using rivets or screws.

A gate 30 is interposed within the cavity between probe 20a and 22a. Gate 30 is pivotally secured to the bottom 11 of the cavity 10 by a means such as hinge 31.- Base 11 is also provided with recess 32 which is adapted to receive gate 30. .Recess 32 has suflicient depth to permit gate 30 to lie flush with the surface of the bottom of cavity 10. A second gate 35 is identical to gate 30. Gate 35 also includes hinge 36 which permits it to assume a horizontal position flush with the bottom of the cavity. Gate 35 may also assume a vertical position between probes 21a and 22a. A gate-operating means 40 includes a mounting plate 41 rigidly secured to bottom 11 of cavity 10. Shaft 42 is rotatably mounted through a bearing 43' which is secured in mounting plate 41. On one end of shaft 42 is a knob; a spur gear 45 is rigidly mounted to the other end of shaft 42. A rack is slidably mounted on mounting plate 41 parallel to the bottom of cavity -10. Rack 54 contains a plurality of teeth 51 which are intermeshed with the teeth of spur gear 45. Each end of a pair of C-shaped connecting links 52 and 53 is pivotally mounted to the end of rack 50 by rivets 54 and 55, respectively. The other end of C-shaped link 52 is pivotally connected to a bracket 56 by a rivet 57. Bracket 56 is rigidly secured to gate 30 by means such as welding. C-shaped member 53 is pivotally connected to gate 35 through a similar bracket 58 and rivet 59. A pair of rivets 60 retains rack 50 against plate 41 and provides a sliding bearing for rack 50.

In operation, if knob 44 is rotated counter-clockwise, rack 50 will move to the left causing gate 30 to rotate about its hinge 31 to a vertical position. Simultaneously, gate 35 will be lowered flush with the inner surface of cavity 10. Since probe 21a forms a coaxial transition between the coaxial input 21 and the waveguide or cavity 10, and since probe 22:: forms a coaxial transition between input 22 and the waveguide or cavity 10 when gate 30 is raised, energy may be transferred between coaxial transition 22a and coaxial transition 21a. Gate 30 will provide a shorted cavity for the coaxial transitions 21a and 22a. In addition to providing the short required for the coaxial transition, gate 30 prevents the energy passing between coaxial transition 22a and 21a that would have reached coaxial transition 20a had not gate 30 been interposed. Therefore, gate 39 provides the additional function of an extremely effective isolation between input 20 and input 22.

If coaxial transition 22 is serving as an input to the cavity, then coaxial transitions 20 and 21 will function as an output. The output may, for example, be connected to separate antennas.

If knob 44 is rotated in the opposite direction, rack 50 will move to the right and cause gate 30 to rotate about its hinge 31 and to lower into recess 32. Gate 35, on the other hand, will simultaneously raise as gate 30 is lowered. Energy, therefore, has been effectively 3 transferred from coaxial transitions 22 and 21 to coaxial transitions 22 and 20.

This switch does not sufier from the limitation of other transmission line switches that incorporate the combination of shutters which are interposed between two open sections of a waveguide. The only openings into the cavity are slots 75 and 76; however, slot 75 or 76 is exposed only when the gate is in a vertical position and no energy could escape therefrom.

FIGURE 2 shows an end view of FIGURE 1 through cross-sectional lines 2-2. Gate 33 is shown in a vertical position completely enclosing the wave guides, while gate 35 is shown in a horizontal position Within the recess in the bottom of the cavity 10 permitting the transfer of power between coaxial transitions 22 and 21.

While coaxial inputs are shown, it is obvious that this switch could be adapted for use as a waveguide switch by eliminating the probes and substituting suitable waveguide inputs. As an example, end 15 and/or 16 could be removed and a suitable waveguide connected thereto. A waveguide input could be substituted for 22a which is supplied with suitable impedance matching devices, such as irises, etc. It is also obvious to one skilled in the art that other operating means could be substituted for the rack and spur gear "as shown in the drawings as, for example, a solenoid. If better isolation were to be desired between the active portion of the guide and the isolated portion of the guide, the gate could be supplied with fingers to provide a better electrical short between the walls of the waveguide and the edges of the gates.

Although this invention has been described with respect to a particular embodiment thereof, it is not to be so limited, as changes and modifications may be made therein which are within the spirit and scope of the invention as defined by the appended claim.

We claim:

A transmission line switch, comprising: wall means defining a rectangular cavity, said wall means having an upper wall and a lower wall spaced from said upper wall,

.3 said lower Wall being relatively thin with respect to said cavity, said wall means also having first and second ends normal to said upper and lower walls; means providing first and second inputs to said cavity respectively adjacent said first and second ends; means providing a third input to said cavity intermediate said first and second inputs; first and second gates, said gates composed of con-' ductive material and of less thickness than said lower wall, said first gate pivotally mounted between and spaced from said first and third inputs and said second gate pivotally'mounted between and spaced from said sec-. 0nd and third inputs; first and second recesses in the lower wall of said cavity and spaced from third input, said first and second recesses being substantially equal in thickness to that of said gates so as to entirely re-,

ceive said first and second gates respectively when said gates are in a position parallel'to said lower wall; and gate-operating means for causing simultaneous. movement of said gates whereby when said first gate is caused to be pivoted to a position normal to said lower wall to interpose a conductive wall between said first and third inputs said second gate is caused to be pivoted so as to be received in said second recess thereby permitting electrical transfer of power between said second and third inputs substantially unimpeded by said second gate and blocking electrical transfer of power between said first and third inputs.

References Cited in the file of this patent UNITED STATES PATENTS 2,423,130 Tyrrell a July 1, 1947 2,513,205 Roberts June 27, 1950 2,647,951 Zaleski Aug. 4, 1953 2,822,526 Wallace et al Feb. 4, 1958 2,917,719 Brown Dec. 15, 1959 FOREIGN PATENTS 897,122 Germany July 8, 1949 

